Thiol-terminated polythioethers are well-known to be useful in aerospace sealant applications. Aerospace sealants must meet a number of demanding performance requirements that include adhesion, tensile strength, elongation, fuel resistance, and high temperature stability. The properties of certain sealant formulations exhibit significant degradation when exposed to high temperatures for an extended period of time. For example, the elongation value of certain thiol-terminated polythioether formulations can decrease to less than 50% following exposure to 300° F. for seven days. Particularly for thiol-terminated polythioethers cured with a polyepoxy, the pendant hydroxyl groups generated by the curing reaction can be a source of free radicals that degrade the physical properties of a cured sealant.
Thiol-terminated polythioether-based sealant formulations exhibiting enhanced high temperature retention of elongation are desired.